R&D Tax Credit Basics for Founders: The Four-Part Test, Section 174A, and the $500,000 Payroll Offset

Founders often hear the research credit pitched as one number. The federal credit under Internal Revenue Code Section 41 is narrower: it applies to specific technical work and costs, and several elections that decide its value are fixed when the original return is filed.

For tax years beginning after 2024, the credit must also be coordinated with Section 174A, which P.L. 119-21 added to restore current deductions for domestic research costs. For filing mechanics, see our startup R&D payroll tax credit guide; for legacy capitalization, see Section 174 capitalization and 174A recovery.

1. The Four-Part Test Applies to Each Business Component

Section 41(d) defines qualified research through four requirements, applied separately to each business component: each product, process, computer software, technique, formula, or invention the company holds for sale, lease, or license or uses in its business.

1. Section 174A test. The costs must be eligible for treatment as domestic research or experimental expenditures under Section 174A, as Section 41(d)(1)(A) now provides.
2. Technological in nature. The work must fundamentally rely on the physical or biological sciences, engineering, or computer science.
3. Permitted purpose. The information must be intended to develop a new or improved business component, judged by function, performance, reliability, or quality rather than style or cosmetic factors.
4. Process of experimentation. Substantially all of the activities, which Treasury Regulation section 1.41-4(a)(6) sets at 80% or more, must evaluate alternatives to resolve uncertainty about capability, method, or appropriate design.

If a whole product does not meet the test, the regulations' shrinking-back rule applies it to the next most significant subset of elements, such as a module. Section 41(d)(4) excludes research after commercial production, adaptation or duplication of existing components, market research and similar studies, foreign research, social sciences, funded research, and internal-use software except as the regulations allow.

Under Treasury Regulation section 1.41-4(c)(6), software built primarily for the company's own general and administrative functions must also meet a high threshold of innovation test; software built for customers to buy, license, or interact with is not internal-use software. Our software R&D tax credit guide covers software claims.

2. What Counts as a Qualified Research Expense

Section 41(b) limits QREs to four categories. Rent, utilities, overhead, and depreciation fall outside the credit base.

The 80% wage rule, the off-premises conditions for computer use, and the contractor conditions come from Treasury Regulation section 1.41-2.

Founder pay matters. A corporate founder who draws no salary generates no wage QREs for personal engineering time. An S corporation owner's reasonable W-2 compensation for qualified services can count; distributions cannot, which is one reason to set S corporation reasonable compensation deliberately. For a partner or sole proprietor with self-employment income, Section 41(b)(2)(D)(ii) treats earned income as wages.

QREs and Section 174A costs will not match. Section 174A expenditures can include overhead and other non-QRE costs; the deduction schedule and credit study should reconcile, not copy each other.

3. Documentation Is Part of the Claim

Treasury Regulation section 1.41-4(d) requires records in sufficiently usable form and detail to substantiate eligibility, and the IRS now asks for part of that file on the return.

• Section G on 2026 returns. Under the Form 6765 instructions, Section G business component reporting is required for tax years beginning after 2025 unless the company is a qualified small business claiming the payroll tax credit, or its controlled-group QREs are $1.5 million or less, its average annual gross receipts for the prior three tax years are $50 million or less, and it is claiming the credit on an original return. When required, Section G covers at least 80% of QREs by component, up to 50 components.
• Amended-return claims. A refund claim that adds or increases the credit must identify the business components, the research activities for each, and total QREs. The IRS research credit claim FAQs waive the names of individuals and the information each sought to discover during a transition period through January 10, 2027.
• Contemporaneous records. Keep tickets, design documents, and test logs showing uncertainty and alternatives; time allocations by person and component; W-2 payroll registers; contractor agreements; and cloud invoices split by environment.

As of October 17, 2026, the IRS About Form 6765 page still listed the December 2024 form and December 2025 instructions as current; confirm before filing.

4. Section 174A and Section 280C: The Deduction-Credit Trade

For tax years beginning after 2024, Section 174A allows a current deduction for domestic research or experimental expenditures, including software development. A company may instead elect under Section 174A(c), by the return due date including extensions, to amortize those costs over at least 60 months.

• Default rule. The company takes the full credit, and Section 280C(c)(1) reduces its Section 174A deduction or capitalized amount by the credit allowed.
• Reduced credit election. Under Section 280C(c)(2), the credit is cut by the product of the credit and the 21% maximum corporate rate, leaving 79%, and no deduction reduction applies. The election is made on Form 6765, Item A, on a timely filed original return including extensions, is irrevocable, and cannot be made or changed on an amended return.

For a C corporation at 21%, the two paths are roughly equal when the deduction is used in the same year. For an S corporation or partnership, the deduction flows to owners whose marginal rate may exceed 21%, which tends to favor the reduced credit. For a loss company, the default path delivers the full credit now and shrinks a net operating loss that may go unused for years. Post-2017 losses generally offset only 80% of taxable income, and an ownership change in a later financing round can limit losses and credit carryforwards under Sections 382 and 383.

5. The 2022–2024 Transition: Status as of October 17, 2026

P.L. 119-21 and Rev. Proc. 2025-28 created relief for domestic research costs capitalized under prior Section 174. The two options limited to small business taxpayers have expired.

The IRS revised the related automatic method change procedures in Rev. Proc. 2026-32, generally effective for Forms 3115 filed after September 4, 2026, with a transition rule for duplicate Forms 3115 filed by November 15, 2026.

6. The Payroll Tax Offset for Early-Stage Companies

Under Section 41(h)(3), a qualified small business is a corporation (including an S corporation), a partnership, or another person such as a sole proprietor, with gross receipts under $5 million for the tax year and no gross receipts in any year before the five-tax-year period ending with that year. Tax-exempt organizations are excluded. Gross receipts are measured under Section 448(c)(3) and Regulations section 1.448-1T(f)(2), which include interest earned on raised capital, and predecessors and controlled-group members count.

The company elects on Form 6765, Section D, to apply up to $500,000 of credit for tax years beginning after 2022, but cannot elect if it made the election for five or more preceding tax years. The election must be made by the due date of the originally filed return, including extensions, not on an amended return. Partnerships and S corporations elect at the entity level.

The credit is claimed on Form 8974 with Form 941, starting with the first calendar quarter that begins after the income tax return is filed. It reduces the employer share of Social Security tax first, up to $250,000 per quarter, then the employer share of Medicare tax, and any remainder carries to the next quarter. For a calendar-year company, filing the 2026 return in March 2027 allows offsets from April 2027; filing on extension in October 2027 delays them to January 2028. Filing timing is a runway decision; see startup cash runway and the tax cash calendar.

7. Dollar Example: Full Credit or Reduced Credit

Common Mistakes

• Counting founder time without wages. Unpaid founder effort produces no wage QREs.
• Counting full contractor invoices. Contract research is generally 65%, and funded research is excluded.
• Missing original-return elections. Neither the Section 280C reduced credit nor the payroll election can be made on an amended return.
• Ignoring interest income and related entities. Investment income, predecessors, and controlled-group members can change qualified small business status.
• Reconstructing records after year-end. Section G and refund-claim rules favor contemporaneous, component-level files.
• Assuming state conformity. State Section 174A treatment and state research credits vary.

The Bottom Line

The research credit rewards documented technical work, not a product category. For a founder, the 2026 decisions converge on one filing: which costs survive the four-part test, whether to take the full credit or the 79% reduced credit, and whether to apply up to $500,000 against payroll taxes. Those elections are made on the timely original return and generally cannot be fixed later, so records, payroll data, and the runway model should be ready before drafting begins. Related support is described on our startups page.

This article provides general educational information about the federal research credit and research expenditure rules as of October 17, 2026. It is not tax advice for any company; eligibility, credit amounts, elections, deadlines, and state treatment depend on facts that require individual review.